It seems that paw_my_constants.h got deleted. I have just verified that is present in the tarball available from download.
I suggest to reopen the tar.gz file.
$ rm Nwchem-6.5.revision26243-src.2014-09-10.tar.gz
$ wget "http://www.nwchem-sw.org/download.php?f=Nwchem-6.5.revision26243-src.2014-09-10.tar.gz" \
-O Nwchem-6.5.revision26243-src.2014-09-10.tar.gz >& /dev/null
$ tar tzf Nwchem-6.5.revision26243-src.2014-09-10.tar.gz|grep paw_my_constants.h